Originally posted by Robbnva
Powerthru and Lower the shoulder slow the ball carrier down, but I have asked in 2 different Q&A sessions if that slow down is enough to cause First step to fire but for some reason that question gets deleted and never answered... 
I just read a Bort quote saying that lower the shoulder slows you down but that power thru does not. Are you sure?
Edit:
Sorry, it was Stiff Arm that had no slow down.
"Question Oct. 21, 2011
Obviously we've seen Spin pretty much takeover and in its absence we tend to see power thru (albeit at a lower clip nowadays). Just wondering if SAs like power thru/Lower the Shoulder are more likely to fire on tackle attempts that are "dead on" while an SA like Stiff Arm or Spin would be more likely to fire on tackle attempts that are made from an angle.
Answer
No, though the effect on the tackler is different between them. Stiff arm will push the tackler to the side, while losing no speed, while power through or lower the shoulder will stop the tackler in his tracks, but slow the ball carrier down. Stiff Arm and lower the shoulder just don't show up as much because they are "lesser" SA's, and spin or power through get a chance to go off first (and if they do go off, we don't even bother with stiff arm or lower the shoulder). If they do go off, their bonus is also lower, so it's less likely they break the tackle, and therefore do not show up. It might actually be interesting to show the icons even on successful tackles. I bet they go off more often than you think."
Edit 2:

"Question April 2, 2011
Lower the Shoulder, Stiff Arm, and power thru What's the difference, mechanically, between them? Lower the Shoulder seems like it's the same thing as power thru only weaker. Are they both flat bonuses to the Break Tackle score who's size depends largely on Strength? Stiff arm is confusing, what is the difference between "avoiding" a tackle and "breaking" one? Is this also strength based, or is Carrying a bigger part of it?
Answer
They are all essentially the same math-wise, just with different strengths. The main differences are the "animations" that happen during or afterward. Stiff arm pushes the defender away sideways, and therefore tends to work better when he's coming from the side. Lower the shoulder will slow you down when you use it, while power through will not."
So... which is it?